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Re: New Proposal (6.1) for GRAPHS

From: Sandro Hawke <sandro@w3.org>
Date: Wed, 28 Mar 2012 10:31:28 -0400
To: Lee Feigenbaum <lee@thefigtrees.net>
Cc: public-rdf-wg <public-rdf-wg@w3.org>
Message-ID: <1332945088.3423.119.camel@waldron>
On Wed, 2012-03-28 at 02:13 -0400, Lee Feigenbaum wrote:
> Hi Sandro,
> 
> First, thanks very much for this.
> 
> Second, I've read through the proposal and -- at least on initial 
> consideration -- strongly support it.
> 
> Third, I do have a comment/question:
> 
> In the Syntax section, you write:
> 
> """
> ISSUE: maybe, for human readability, we can allow graphs to be spread 
> throughout the document, so "<u1> { <a> <b> 1 } <u1> { <a> <b> 2 }" 
> would parse to the same dataset as "<u1> { <a> <b> 1. <a> <b> 2 }"
> """
> 
> But the rest of the wiki page seems to preclude this (e.g. 
> http://www.w3.org/2011/rdf-wg/wiki/Graphs_Design_6.1#Test_10). Perhaps 
> this test is talking about the abstract syntax, post-parsing?
> 
> We strongly support allowing graphs "to be spread throughout the 
> document" in the way that the "ISSUE: ..." comment suggests. We do this 
> all the time when writing out large data sets to disk, as it is often 
> impractical to write all of the statements for a particular graph at the 
> same point within a trig file.

Okay, that's enough for me, unless someone has a big problem with it.

> Dare I ask what the domain of rdf:hasGraph is? Is it anything meaningful 
> / name-able? Is it a "graph label" (which is not disjoint with graphs)? 
> Happy to unask this if I should. :-)

To me, the domain of rdf:hasGraph is rdf:Resource.  A big advantage of
this design is, I think, it allows for some of the funky ways SPARQL is
using datasets now, like using the primary subject of the graph as the
label.

I'm not sure everything works perfectly if you go that direction, but I
don't think it's entirely ruled out.     (In particular, you could try
to formalize it, by making a class :PrimarySubject or something, but
that's kind of broken, because it's only the primary subject in this
particular dataset -- that's not really a class of the thing itself.)

   -- Sandro

> thanks,
> Lee
> 
> On 3/27/2012 10:23 PM, Sandro Hawke wrote:
> > I've written up design 6 (originally suggested by Andy) in more
> > detail.  I've called in 6.1 since I've change/added a few details that
> > Andy might not agree with.  Eric has started writing up how the use
> > cases are addressed by this proposal.
> >
> > This proposal addresses all 15 of our old open issues concerning graphs.
> > (I'm sure it will have its own issues, though.)
> >
> > The basic idea is to use trig syntax, and to support the different
> > desired relationships between labels and their graphs via class
> > information on the labels.  In particular, according to this proposal,
> > in this trig document:
> >
> >     <u1>  {<a>  <b>  <c>  }
> >
> > ... we only know that<u1>  is some kind of label for the RDF Graph<a>
> > <b>  <c>, like today.  However, in his trig document:
> >
> >     {<u2>  a rdf:Graph }
> >     <u2>  {<a>  <b>  <c>  }
> >
> > we know that<u2>  is an rdf:Graph and, what's more, we know that<u2>
> > actually is the RDF Graph {<a>  <b>  <c>  }.  That is, in this case, we
> > know that URL "u2" is a name we can use in RDF to refer to that g-snap.
> >
> > Details are here: http://www.w3.org/2011/rdf-wg/wiki/Graphs_Design_6.1
> >
> > That page includes answers to all the current GRAPHS issues, including
> > ISSUE-5, ISSUE-14, etc.
> >
> > Eric has started going through Why Graphs and adding the examples as
> > addressed by Proposal 6.1:
> > http://www.w3.org/2011/rdf-wg/wiki/Why_Graphs_6.1
> >
> >       -- Sandro (with Eric nearby)
> >
> >
> >
> 
Received on Wednesday, 28 March 2012 14:31:45 GMT

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